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In addition to previously reported 25-norhopanoic acids with the 17α(H), 21β(H) and 17β(H), 21α(H) configurations, for the first time we report the identification of 25-norhopanoic acids bearing the 17β(H), 21β(H) configuration in a suite of heavily biodegraded oils from China. The 17β(H), 21β(H) stereochemistry is a thermally unstable biologically-derived structure, suggesting that the 17β(H), 21β(H) 25-norhopanoic acids may derive from petroleum-degrading microbes. Rather than representing a direct input, we propose that demethylation of 17β(H), 21β(H) hopanoic acids derived from bacteria in the reservoir may give rise to 17β(H), 21β(H) 25-norhopanoic acids, implying that microbial reworking of biomass is occurring alongside petroleum degradation.

Pristane (2,6,10,14-tetramethylpentadecane), frequently the most abundant biomarker hydrocarbon in crude oils and rock extracts, was thought originally to be derived directly from phytol or, later, from thermal degradation of tocopherols. We present new evidence supporting the hypothesis that pristane, under certain conditions, may result from the catagenic decomposition of methyltrimethyltridecylchromans (MTTCs) derived during diagenesis from condensation reactions between chlorophyll and alkylphenols. We show that phytol can condense, under mild conditions, with phenolic systems (in free or polymeric form) to produce free or bound structures that generate pristenes on flash pyrolysis. We suggest straightforward tests of this hypothesis.

General procedures are outlined for the asymmetric syntheses of lignans of the dibenzylbutyrolactone, dibenzylbutanediol, aryltetralin and dibenzocyclooctadiene series, from tandem addition products derived from 4-menthyloxybutenolide.

Bioremediation and activated carbon (AC) amendment were compared as remediation strategies for sediment from the River Tyne containing 16.4 +/- 7.3 microg/g polycyclic aromatic hydrocarbons (PAHs) and approximately 5% coal particles by total dry sediment weight. Unamended, nutrient amended (biostimulated) and nutrient and Pseudomonas putida amended (bioaugmented) sediment microcosms failed to show a significant decrease in total sediment PAH concentrations over a one month period. Polyethylene passive (PE) samplers were embedded for 21 days in these sediment microcosms in order to measure the available portion of PAHs and accumulated 4.70 +/- 0.25, 12.43 +/- 1.78, and 23.49 +/- 2.73 microg PAHs/g PE from the unamended, biostimulated, and bioaugmented microcosms, respectively. Higher PAH uptake by PE samplers in biostimulated and bioaugmented microcosms coincided with slower degradation of spiked phenanthrene in sediment-free filtrate from these microcosms compared to filtrate from the unamended microcosms. Microbial community analysis revealed changes in the bacterial community directly following the addition of nutrients, but the added P. putida community failed to establish itself. Addition of 2% by dry sediment weight activated carbon reduced PAH uptake by PE samplers to 0.28 +/- 0.01 microg PAHs/g PE, a greater than 90% reduction compared to the unamended microcosms.

Addition of sulphur stabilised carbanions to a chiral non-racemic butenolide followed by reaction with an aromatic aldehyde affords a short synthesis of homochiral dibenzylbutyrolactone derivatives. Desulphurisation of the first formed adducts proceeds in almost quantitative yield to afford the parent lignan.

A field-scale experiment with a complete randomized block design was performed to study the degradation of buried oil on a shoreline over a period of almost 1 year. The following four treatments were examined in three replicate blocks: two levels of fertilizer treatment of oil-treated plots, one receiving a weekly application of liquid fertilizer and the other treated with a slow-release fertilizer; and two controls, one not treated with oil and the other treated with oil but not with fertilizer. Oil degradation was monitored by measuring carbon dioxide evolution and by chemical analysis of the oil. Buried oil was degraded to a significantly greater extent in fertilized plots, but no differences in oil chemistry were observed between the two different fertilizer treatments, although carbon dioxide production was significantly higher in the oil-treated plots that were treated with slow-release fertilizer during the first 14 days of the experiment. Bacterial communities present in the beach sediments were profiled by denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene fragments and 16S rRNA amplified by reverse transcriptase PCR. Similarities between the DGGE profiles were calculated, and similarity matrices were subjected to statistical analysis. These analyses showed that although significant hydrocarbon degradation occurred both in plots treated with oil alone and in the plots treated with oil and liquid fertilizer, the bacterial community structure in these plots was, in general, not significantly different from that in the control plots that were not treated with oil and did not change over time. In contrast, the bacterial community structure in the plots treated with oil and slow-release fertilizer changed rapidly, and there were significant differences over time, as well as between blocks and even within plots. The differences were probably related to the higher concentrations of nutrients measured in interstitial water from the plots treated with slow-release fertilizer. Bacteria with 16S rRNA sequences closely related (>99.7% identity) to Alcanivorax borkumensis and Pseudomonas stutzeri sequences dominated during the initial phase of oil degradation in the plots treated with slow-release fertilizer. Field data were compared to the results of previous laboratory microcosm experiments, which revealed significant differences.

Degradation of oil on beaches is, in general, limited by the supply of inorganic nutrients. In order to obtain a more systematic understanding of the effects of nutrient addition on oil spill bioremediation, beach sediment microcosms contaminated with oil were treated with different levels of inorganic nutrients. Oil biodegradation was assessed respirometrically and on the basis of changes in oil composition. Bacterial communities were compared by numerical analysis of denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified 16S rRNA genes and cloning and sequencing of PCR-amplified 16S rRNA genes. Nutrient amendment over a wide range of concentrations significantly improved oil degradation, confirming that N and P limited degradation over the concentration range tested. However, the extent and rate of oil degradation were similar for all microcosms, indicating that, in this experiment, it was the addition of inorganic nutrients rather than the precise amount that was most important operationally. Very different microbial communities were selected in all of the microcosms. Similarities between DGGE profiles of replicate samples from a single microcosm were high (95% ± 5%), but similarities between DGGE profiles from replicate microcosms receiving the same level of inorganic nutrients (68% ± 5%) were not significantly higher than those between microcosms subjected to different nutrient amendments (63% ± 7%). Therefore, it is apparent that the different communities selected cannot be attributed to the level of inorganic nutrients present in different microcosms. Bioremediation treatments dramatically reduced the diversity of the bacterial community. The decrease in diversity could be accounted for by a strong selection for bacteria belonging to the alkane-degrading Alcanivorax/Fundibacter group. On the basis of Shannon-Weaver indices, rapid recovery of the bacterial community diversity to preoiling levels of diversity occurred. However, although the overall diversity was similar, there were considerable qualitative differences in the community structure before and after the bioremediation treatments.

Enolate anions obtained by conjugate addition to (–)-5-(1-menthyloxy)furan-2(5H)-one are quenched with benzyl bromides or iodides to yield homochiral dibenzylbutyrolactones. Desulfurisation followed by lithium aluminium hydride reduction affords homochiral 2,3-dibenzylbutane-1,4-diols, including (–)dimethylsecoisolariciresinol and (–)-dihydroclusin. Desulfurisation followed by reduction with NaBH4/KOH gives the homochiral 2,3-dibenzylbutyrolactones (–)-dimethylmatairesinol, (–)kusunokinin and (–)-yatein, which undergo stereoselective oxidative coupling with DDQ in trifluoroacetic acid to give homochiral tetrahydrodibenzocyclooctene lignans belonging to the isostegane series.

Addition of sulfur-stabilised carbanions to (–)-5-(1-menthyloxy)furan-2(5H)-one followed by reaction with an aromatic aldehyde affords a short synthesis of enantiomerically pure dibenzylbutyrolactone derivatives. Desulfurisation with NaBH4/NiCl2 proceeds in almost quantitative yield, and reduction with NaBH4/KOH gives the parent dibenzylbutyroactones including (–)-6-epi-podorhizol. These undergo cyclisation with acid to give homochiral aryltetralins including (–)-deoxyisopodophyllotoxin in high yield.